I. Field of the Invention
The present invention relates generally to a package for an item. More particularly, the present invention relates to a package specifically designed to isolate from contamination materials used in the manufacture of electronic semiconductor components and circuits. Such packages are particularly well suited for substrates, wafers, memory disks, photomasks, flat panel displays, liquid crystal displays, and the like.
II. Description of the Prior Art
Various containers have been used for centuries to transport items from one place to another. Such containers have, for example, been used to provide a way to confine items in a space for efficient storage. Such containers also provide an easy way of handling items. Another important function provided by packages and containers is protection.
Substrates used in the manufacture of semiconductor circuits, rigid memory disks, photomasks, liquid crystal displays, and flat panel displays can be extremely sensitive. Effective steps must be taken to protect such items from damage by moisture, particles, static electricity, or the like. Steps must also be taken to protect the articles from damage caused by vibration and shock within the package. Similarly, steps must be taken to prevent outgassing and the generation of particles which will occur if the items stored in the package scrape, rub, or impact various surfaces within the package.
This combination of problems makes designing a suitable package very difficult. Such problems are only compounded by the environment in which such packages are typically used.
Suitable packaging for use in connection with the storage and transport of wafers, memory disks, photomasks, liquid crystal display panels and flat panel displays tend to be very expensive. It is highly desirable that such packaging be reusable and have durable construction. Also, such packaging must be capable of being readily and thoroughly cleaned. Finally, when the package is used in connection with the manufacture of semiconductors, it must be readily adaptable for use with robotic handling and automated manufacturing equipment.
Empak, Inc., has made a number of suitable packages in the past for use in the processing and transport of such items. Examples of such packages are shown in U.S. Pat. No. 5,273,159 and U.S. Pat. No. 5,423,422. While such package designs have proven to be highly effective in conjunction with smaller items, the designs, for a variety of reasons, are not suitable for storage and transport of items having outside dimensions in the range of 300 mm or more.
Suitable containers for use with wafers, photomasks, memory disks, liquid crystal display panels and flat panel displays must meet several important design criteria. They must be light weight to make manual and robotic handling tasks easier. The internal volume of the container should be minimized to reduce storage space requirement and increase storage density. The height of the container should be minimized to allow for improved stacking of the containers. The amount of polymer surface area surrounding the items during transport and storage should be minimized to reduce inorganic and organic contaminants as well as the negative affects of outgassing of the polymer.
Containers built in accordance with the present invention meet the design criteria set forth above. Such containers also provide several other unique advantages. First, tolerance build-up is minimized by means of locating the container about item center lines, thereby increasing the positional accuracy of the items stored in such containers. This enhances effective insertion and removal of the items from the container using robotic equipment. Second, the containers reduce the risk of damage caused by static electricity. This is achieved in one preferred embodiment by providing a conductive path to ground from static dissipative internal item supports to the container""s external kinematic coupling plate which is used to position the container on various pieces of equipment. Third, the containers of the present invention are designed to be wet-cleaned with or without disassembly. Fourth, since the containers of the present invention can have an integral design which does not require a separate carrier, the containers can remain associated with a specific lot of items. This enables workers in the factory to better track a lot and, therefore, reduces the chance of processing errors. Fifth, the integral design, by eliminating the need for a separate cassette, minimizes the number of packaging components required to be kept in inventory and the space such components take up. Sixth, the integral design eliminates the need to accurately position a removable cassette in the container and lock it in place. Finally, the integral design can be manufactured using fewer and smaller parts, thereby reducing manufacturing costs.
It is therefore an object of the present invention to provide an isolation container which will provide protection against contamination by particles or moisture.
Another object of the present invention to provide a container which protects the items stored therein from damage due to shock and vibration and from damage due to the item scraping, rubbing, or impacting various surfaces of the container.
A further object of the invention is to provide such a container which is reusable and easily cleaned.
Still another object of the invention is to provide such a container which has interior structures which are not susceptible to wear or generation of particles which could contaminate the contents of the package.
Yet another object of the invention is to provide such a container which is highly effective when used in conjunction with automated processing or handling equipment.
Still another object of the invention is to provide a structure which can easily be handled, manipulated and transported by humans.
These and other objects are accomplished by providing a container having a shell with an opening for insertion and removal of the items, a door designed to effectively seal the opening, a plurality of item-retaining structures within the shell which securely hold the items and retain them in spaced apart relation from each other, a kinematic coupler plate to assist in aligning the container with the port of equipment used to process the items in a factory, and ergonomically designed handles which can be effectively used either manually or through robotic means. In order to reduce contamination by particles inside the container, the item supports are made of a high-temperature resistant, conductive material. The item supports are also grounded to the exterior of the container as described in detail below. The entire container is structured to maximize the support and protection offered to the items, maximize ease of handling, and reduce, to the extent possible, the height and weight of the container.
A better understanding of the invention will be deserved from reading the description of the preferred embodiment set forth below in conjunction with the drawings. While the description and drawings specifically relate to a microenvironment pod for silicon wafers, the invention described is also well suited for other applications, such as the storage and transport of photomasks, rigid memory disks, liquid crystal display panels, flat panel displays, or the like.